V‐band millimeter‐wave microstrip to rectangular waveguide transition

This article proposes a novel millimeter‐wave microstrip (MSL) to WR 12 standard rectangular waveguide transitions. These dissimilar structures are interconnected via a substrate integrated waveguide (SIW). The MSL and the SIW are integrated on the same ceramic substrate of 9.9 relative permittivity and 125 μm thickness. The MSL was first transformed into an air‐filled rectangular waveguide, and then a stepped impedance or horn transformer was used to match the WR12 standard rectangular waveguide. The central frequency of operation is 61 GHz as required in V‐band wireless communications applications. Commercial Finite Element Method Software and High Frequency Structure Simulator (HFSS) was used to perform the design and the optimization. The S parameter measurements of the back‐to‐back connected transitions show an insertion loss less than 1.5 dB and a return loss better than −10 dB over a 4 GHz band from 60 to 64 GHz. The high performance, the compact size, and the simple fabrication, enable similar transitions to be employed in a number of other millimeter‐wave applications.